Flock of Magpie Larks

I need to go for regular walks for the good of my health. These walks regularly give me opportunities to do a little birding as I go. A few evenings ago, just on sunset, I saw 21 Magpie Larks all flying overhead in the same direction. I have normally only observed single birds or a pair. Most often one only experiences a few at a time, rarely in large groups.

On checking the handbook of Australian Birds (HANZAB) I have discovered that flocks of up to 100 individuals have been seen. I am not sure where they had been but they all seemed to be heading for a nearby oval, possibly to roost in the trees next to the oval.